The present invention relates to a pouch or sack for packing a material therein, and more particularly, to the pouch having a tearing zone for taking out the material packed therein.
A composite film is generally available as a material of a sack or pouch. The composite film includes a polyethylene film laminated on an ordinary cellophane sheet or paper. The composite film having a rectangular shape is folded and confronting side edge portions are heat-sealed together so as to provide fluid-tight pouch. Alternatively, two composite films having shapes identical with each other are overlapped with each other, and confronting four side edge portions are heat-sealed together. When the pouch or the sack formed of such laminated film is required to be opened, a heat-sealed portion of the pouch can be manually torn, i.e., a user can manually break the seal at the heat-sealed portion. Such type of pouch is widely used.
Another type of pouch 1 formed of plastic laminated film is shown in FIG. 1 so as to improve fracture strength and moisture resistivity, so that fluidized content such as cooked food can be sealingly packed therein. However, the plastic laminated film provides relatively high tearing strength, and therefore, it would be rather difficult to manually tear the pouch at a heat-sealed portion 2 to take out the material.
In order to solve this problem, v-shaped or I-shaped notch 3 is formed at the heat-seal portion 2 so as to concentrate tearing force thereat and to propergate the force along the tearing direction A. In this case, if the content is not fully packed in the pouch, the user can hold only the films of the pouch, and it can be easily torn along the direction A. However, if the content is fully packed in the internal space of the pouch 1, such content may interrupt the tearing action. For example, if the content may be the frozon food fully packed in the pouch, the user cannot easily tear the pouch along the direction A, since the solidified content may interfere with the manual tearing action.
Still another type of a pouch 10 is shown in FIG. 2. The pouch 10 is formed of a cellophane or polypropylene film to pack therein a content such as a cigarette case 11. According to this type, the case 11 is fully occupied in the internal space of the pouch 10. However, there is provided a tearing zone 12 along which the pouch 10 can be easily torn for taking out the content. In the tearing zone 12, a tape 12a is bonded to the inner surface of a sheet 10a of the pouch 10, and the tearing zone 12 is defined by the internal tape 12a and a part 12b of the sheet 10a. Tensile strength of the tape 12a is higher than that of the pouch material 10a, so that when a leading end 12c of the tearing zone 12 is manually held and the user pulls up the leading end 12c, the pouch can be torn along the tearing zone 12 as shown by a dotted-chain line in FIG. 2. If required, additional tape-like film (not shown) is provided at inner side of the tape 12a so as to sandwich the same between the outer sheet 10a and the innermost additional tape-like film.
According to this conventional structure, even if the content is fully packed in the pouch 10, the user can easily open the pouch without being interfered with by the content. However, this latter type of pouch has disadvantages in that it would be rather difficult to manufacture the pouch, since an intricate tape bonding step is required prior to making the three dimensional pouch, and sufficient strength of the sheet 10a is not obtainable, since its strength must be lower than that of the internal tape 12a. Further, if a difference in tensile strength is not provided between the tape 12a and the sheet 10a, then slits or minute perforations must be formed at the sheet 10a so as to pull up the tearing zone 12 along the slits in the direction shown by the one-dotted line, which in turn, degrades sealability. Furthermore, if the inner tape 12a is accidentally cut during tearing, further opening is not be easily achievable.